1. Field of the Invention
The present invention relates to a stack fastening device for a molten carbonate fuel cell and, more particularly, to a stack fastening device in which a hydraulic unit is detachably installed on a stack fastening section and a load cell and a cooling unit are installed on the lower end of a vertical beam so that compressive force can be applied using a hydraulic cylinder and changes in a stack and in compressive force can be continuously monitored.
2. Description of the Prior Art
As is generally known in the art, a fuel cell serves as an electric power generation device for converting chemical energy, obtained through the oxidation and reduction of a reactant, into electrical energy. In the fuel cell, only water is discharged as a byproduct, unlike other existing kinds of chemical energy. Therefore, since the fuel cell does not cause any environmental pollution, does not generate noise, and features a simple reaction, the fuel cell has been highlighted as a next-generation alternative energy source.
In particular, among fuel cells, a molten carbonate fuel cell (MCFC) has an operating temperature no lower than 600° C., since it uses a molten carbonate as an electrolyte. Thus, the electrochemical reaction can occur rapidly, unlike a fuel cell operating at a low temperature, a catalyst made of a noble metal, such as platinum, is not needed. In the case that electricity and high temperature are simultaneously used, thermal efficiency greater than 80% can be anticipated, and combined cogeneration due to coal gasification is possible.
The unit cell of the molten carbonate fuel cell is composed of an anode and a cathode, at which the electrochemical reaction occurs, a separation plate for defining flow paths for a fuel gas and an oxidant gas, a charge collecting plate for collecting electric charges, an electrolyte and a matrix for accommodating molten carbonate. In the molten carbonate fuel cell, by supplying the fuel gas to the anode and the oxidant gas to the cathode, the electrochemical reaction occurs at the anode and the cathode, by which DC power can be obtained.
The voltage of the unit cell has a low value of about 0.7˜1.2V on rated discharge. Hence, for actual generation, a plurality of unit cells is stacked to raise the voltage, and the area of the unit cell is increased to accomplish a high output. The structure in which the plurality of unit cells is stacked is called a stack.
In the stack, since the plurality of unit cells is stacked upon one another, if a gap is formed between unit cells, problems are caused in that internal resistance is generated and the electricity cannot flow smoothly. In order to cope with these problems, in the stack, the contact force between unit cells is increased using a stack fastening device so as to decrease the internal resistance thereof, and compressive force is applied so as to ensure the smooth flow of electricity.
However since in the conventional stack fastening device, a hydraulic cylinder is fixedly installed on a stack, the hydraulic cylinder cannot be used at high temperatures such as 600° C., which is the operating temperature of the stack
Also, in the conventional stack fastening device, because the stack is held in a state in which it is simply locked between upper and lower plates after compression force is applied to the stack, the situation in which the height of the stack is changed cannot be flexibly dealt with.
Further, in the conventional stack fastening device, due to the fact that changes in the stack and the compressive force cannot be continuously monitored, it is difficult to adjust the magnitude of the compressive force applied to the stack. As a consequence, in the conventional stack fastening device, because changes in the stack cannot be continuously monitored, in the case where the magnitude of the compressive force applied to the stack is increased, excessive force is applied to the stack and respective unit cells are likely to break. Conversely, in the case where the magnitude of the compressive force is decreased, the contact force between the unit cells becomes insufficient and the smooth flow of electricity cannot be ensured, whereby the voltage cannot be supplied in an adequate manner.